Three down - that's good! Let's wait a day or two for a fourth lucky
colaborator: the entry fee is down to $25 for the next person....
Brian
///The CR-39 detectors of alpha particles are also
suitable for noncontroversial student projects, for
example, a study of distribution of radon///
The detector, called CR-39; is a sheet of transparent
plastic. Alpha particles, for example, from radon, create
latent tracks which can be made visible (through a
microscope) by developing pieces of CR-39 in hot
KOH.///